Lockbolts of the type having grooved or threaded shanks adapted to receive a swagable metal collar have been known and in widespread use since at least as early as the application date of U.S. Pat. No. 2,521,048 incorporated by reference into expired U.S. Pat. No. 4,852,736 assigned to Huck Manufacturing Company. A typical lockbolt comprises a head and a shank extending from the head. In some cases, the shank is divided into two axially-spaced portions separated by a fracture groove. The portion closer to the head is provided with convolutions or grooves, onto which a collar is swaged. The shank portion farther from the head is called a “pintail” and is broken off by a puller within the swaging tool.
In practice, lockbolts are placed in holes preformed in the workpieces to be joined. Thereafter, a worker assigned to finish the installation of the lockbolts places collars on a number of lockbolt shanks and then applies the swaging tool to set the collars and, where applicable, break off the pintail. This is done lockbolt-by-lockbolt in sequence. A worker typically swages collars in groups of, for example, 6 to 12 collars, and then rests his or her arms by lowering the swaging tool and placing collars on the next set of lockbolts to be finished. We refer to the swaging of a group of lockbolt collars in one tool-handling time as a “cycle”, it being understood that most fastening jobs involve a number of such cycles.
As a practical matter, there are several problems that can crop up in the field. The first arises out of the fact that the article being constructed is sometimes above the worker's head, and the lockbolt shanks may be vertical. Even if a sticky substance like rubberized cement is used to hold the unswaged collars in place, the swaging process may still cause collars to fall off of the lockbolt shanks before they are swaged. In aircraft applications, dropped collars must be scrapped. This not only reduces the efficiency of the lockbolt installation process, but also requires a worker to prevent dropped collars from becoming “foreign object debris” (FOD).
Another problem which often arises in the field is the collection and disposal of lockbolt shank pintails broken off during the swaging step. The typical tool simply ejects pintails without any kind of organization or collection function. Ejected pintails often collect on or around the workpiece or fall on the floor where they present a safety hazard. This is another potential source of FOD. Moreover, normal collection further reduces lockbolt installation efficiency.